The present invention relates to an interrogation device and specifically a Doppler-guided nerve stimulator device which accurately localizes and positions a puncture needle or other surgical probe into a neurovascular bundle or near a nerve. This invention has application in a variety of medical procedures, and has particular utility in regional anesthesia procedure. The neurovascular bundle includes a fibrous sheath or fascial compartment surrounding a nerve and a vessel. The ability to perform regional anesthesia requires the very precise placement of the appropriate drug inside of a neurovascular bundle innervating the region to be anesthetized. Previously, localization and puncture of the neurovascular bundle has been dependent on the skill of the operator either in guiding an appropriately beveled needle, or in following the motor responses elicited by a nerve stimulator attached to a conductive electrode. Devices of this latter type are known as nerve stimulator electrodes. However, as listed in Plexus Anesthesia Vol. 1 by A. Winnie M.D., because the neurovascular bundle travels near vital structures, these devices are associated with operator error and well recognized morbidity and mortality. For example, in the upper extremities the neurovascular bundle has a posterior, superior position in relation to the clavicle. Closely apposed to the bundle is the pleura and substance of the lung. Inaccurate placement of a needle into the lung can result in pneumothorax while inadvertent injury to a vessel can result in hemothorax. Long term nerve injuries after blind injection into the neurovascular bundle are well known. Separate but equally serious injuries can occur to structures adjacent to the neurovascular bundle when the anatomy is obscured, minimize nearby structure or vascular injury and allow easy confirmation of position within the neurovascular bundle.
One example of an interrogation device is shown in U.S. Pat. No. 3,830,226 to Staub et al. This device is a variable output nerve locator that permits stimulation of an exposed nerve by the application of electrical energy to the nerve. This device however does not use a guide needle, will not allow administration of medications or the introduction of other instruments into the neurovascular bundle, and requires exposure of the nerve surgically. A second example is shown in U.S. Pat. No. 4,824,433 to Marz et al. Marz discloses a puncturing and catheterizing device for the human or animal body which uses a conductive puncture needle and a surrounding cannula. The device is specifically intended for nerve tracts and allows the use of an attached nerve stimulator. This device allows only electrical stimulation to be used to provide directional information and does not allow the attachment of different sensors to the puncture needle and cannula. A third and different type of device is disclosed in U.S. Pat. No. 4,887,606 by Yock for cannulation of a vessel. This device relies upon an ultrasound transducer attached to the tip of a trocar positioned within a hollow needle for transmitting and receiving ultrasonic waves through the sharpened end of the needle. The device can be guided in response to the backscattered ultrasound energy reflected from flow within the vessel until the vessel is cannulated. However, the patent does not disclose any means or method of distinguishing the vessel from the neurovascular bundle nor any means or method for locating or avoiding the nerves contained within a bundle should it be used for cannulation of a vessel contained within a neurovascular bundle. Nor does the device assure localization of the sharpened needle tip within a neurovascular bundle or in close proximity to a selected nerve. It also does not allow the addition of other sensors such as a nerve stimulator or allow the use of a bipolar stimulator design.